| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 가을 (10/13 ~ 10/14, 제주 ICC) |
| 권호 | 30권 2호 |
| 발표분야 | 고분자 합성 |
| 제목 | Synthesis and Characterization of Novel Polymeric Photoacid Generators for Direct Photochemical Modification of Surface |
| 초록 | In recent years, a number of studies have focused on deoxyribonucleic acid (DNA) microarrays consisting of hundreds to millions of sequences immobilized on a supporting surface, which are anticipated to have a significant impact on a number of emerging biotechnology areas, such as DNA chip technology.1-3 There are two basic approaches, on-chip synthesis4,5 and spotting,6,7 to immobilizing the variety of sequences used in probe DNA on solid surfaces. The on-chip method uses a photolithographic process and can array many more oligonucleotide probes on a limited area of a chip than the spotting method.8,9 According to previous reports, the photolithographic processing required by the on-chip method has been carried out with a general photoresist (PR) method4 and with a photoacid patterned array (PPA) method.5 Photolithographic processing with PR has the advantage of using materials that are already developed and commercialized for the semiconductor industry. This approach provides satisfactory high resolution, but the complexity of such processing, including PR pattern formation, the removal of protecting groups with an acidic solution, and the attachment of nucleic acids, is a major drawback. To simplify the processing and improve efficiency, the PPA method, which uses a polymeric matrix mixed with PAG, has been proposed. In this approach, acids are generated only at the exposed region and the removal of protecting groups occurs after heat treatment, so the two separate steps required by the PR method can be carried out with the PPA method in one step.5 However, the PPA method also has several problems. For example, the acid generated from the PAG by UV exposure remains on the polymer matrix, and should preferably diffuse from the polymer to the substrate surface. However, the generated acid may diffuse in the opposite direction from the protection groups when the glass substrate is heated on a hot plate, thereby reducing the efficiency. In addition, the photogenerated acid is captured by deprotected amine groups through acid-base reactions, which also reduces the efficiency. For these reasons, more PAG is required. However, above a certain level of PAG, PAG domains form that scatter light, which in turn interferes with fine pattern formation. Further, when the PAG is used on its own, it is not possible to produce thin films by spin coating. To overcome these limitations, we have synthesized a novel polymeric PAG for the lithographic processing of DNA chips. In this paper, we describe the synthesis and characterization of this novel polymeric PAG. The polymeric PAG is a polymer with a molecular weight in the range from 3,400 to 4,000, and has a sulfonium salt in its backbone. Thus, the PAG’s acid-generating moiety content is effectively increased without the problems of phase separation or diffusion. We also carried out lithographic evaluations. The acid generated from the polymeric PAG was found to effectively deprotect the acid-labile groups of the linker molecules in the exposed region by a chemical amplification process, and enable the fabrication of a well-defined pattern of linker molecules at the micro level. |
| 저자 | 정성욱, 정명섭, 허남 |
| 소속 | 삼성종합기술원 |
| 키워드 | polymeric photoacid generator; surface modification; microarray; DNA chip |
